Fan stopped when no audio input

Circuit which is also equipped with temperature sensors would protect the high temperature. However, in the above circuit which necessiatated the input of the amplifier / audio signal. The way it works is , if the amplifier circuit to work and ouput signal to be connected to this circuit , Fan 12V will work well. If the received audio signal this circuit does not exist , then the fan 12V die. And automatic circuit amplifier also not work and does not require refrigeration.

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